The Opal Nugget Ice Maker machine had all the usual hallmarks of a crowdfunded hit. Engineers from FirstBuild, the project’s creator, posted videos of their design prototype, filmed inside a tool-strewn workshop, and talked openly about the remaining technical challenges before their machine would be ready for delivery in mid-2016. It looked like a typical invention dreamed up by a scrappy team seeking cash for manufacturing — except that FirstBuild is a subsidiary of General Electric.